Field of the Invention
The present invention relates to a system for the preparation of beverages by infusion, using prepackaged capsules, preferably of the sealed type, containing a quantity of a substance, for example ground roast coffee, for the preparation of a beverage.
Background
More specifically, the invention relates to a system comprising, in a known way,                capsules having a cup-shaped body with a mouth opening closed by a cover, a bottom wall and an annular side wall which extends between the mouth opening and the bottom wall, tapering towards said bottom wall; said capsules being of at least first and second types, having essentially equally-sized bottom walls and different axial lengths; and        an infusion assembly wherein there is defined a variable-volume infusion chamber, having an introduction opening, an end delimitation part having a shape and dimensions corresponding to those of the bottom wall of said capsules, and with a lateral delimitation structure which comprises a static portion which extends between said introduction opening and the end delimitation part;        the end delimitation part being movable inside the lateral delimitation structure away from the introduction opening;        the arrangement being such that one of said capsules, introduced into the infusion chamber, is capable of causing a movement of the end delimitation part away from the introduction opening, such that the infusion chamber assumes a configuration and dimensions corresponding to those of the type of capsule introduced thereinto.        
A system of this type for the preparation of beverages is described and illustrated in European patent application EP 1 208 782 A1.
In this known system, a capsule, selectively of a first or a second type, is made to bear on a loading plate which, by means of a manually operated control lever, is then translated horizontally and subsequently raised vertically, so as to introduce this capsule into the infusion chamber formed in a percolation unit. The arrangement is such that the operation of the control lever simultaneously causes a lowering of the percolation unit. The latter comprises a fixed lateral delimiting structure of the infusion chamber, in which an end delimiting part of said chamber is vertically slidable in a liquid-tight way. Because of the coupling between the loading plate and the percolation unit, the capsule introduced into the infusion chamber causes a movement of the end delimiting part of this chamber, as a function of the axial length of the capsule.
With this known system, it is essentially possible to differentiate between the volumes of the different types of capsules solely by providing them with different lengths or heights, and therefore the larger-volume capsules have a rather pronounced height; in other words they are rather long.
One object of the present invention is to provide an improved system for the preparation of beverages of the type defined initially.